Such gas springs are also used, inter alia as lifting axiliaries for rear flaps of cars. Precisely in the case of relatively small cars the lifting force of one gas spring only is sufficient to lift the rear flap; however, the problem arises here that precisely because of the light construction of small private cars and of the presence of only one gas spring the rear flap becomes distorted. Therefore, numerous attempts have already been made at relieving the pressure on the rear flap in the closed state. The solutions found were unsatisfactory, functionally and/or because of the necessary expenditure.